Brooding

Understanding the effects climate change may
have on animal populations relies on establishing which
environmental conditions shape their behaviour and subsequent
reproductive output, fitness or survival. South
Africa has seen significant warming trends and changes in
precipitation over the last few decades; however, the ways
in which these trends are likely to influence animal
populations are still relatively poorly understood. The Black
Sparrowhawk (Accipiter melanoleucus) has expanded its
range in South Africa and recently colonised the Cape
Peninsula in the Western Cape, a region that experiences a
Mediterranean climate. In this study, we examined the
brooding behaviour of this species, a vital trait for reproductive
success, in the Cape Peninsula breeding population.
We examined the influence of chick age as well as temperature,
rainfall and wind speed on parental brooding.
Additionally, the effect of prey provisioning on brooding
was investigated. In our analyses, we used data on brooding
from nest cameras together with weather data collected at a
fine temporal scale (1 h). The variable with the strongest
influence on parental brooding was chick age. This variable
showed a non-linear relationship. Initially chicks were
brooded [50 % of the time; however after 3 weeks
brooding declined rapidly. The proportion of time spent
brooding increased with decreasing temperatures, while
rainfall and wind speed showed a positive correlation with
the amount of brooding. Our model predicted that in common
winter conditions of the Western Cape (15 C, 10 km/
h wind speed, 1 mm/h rainfall) A. melanoleucus breeding
pairs spent nearly 100 % of their time brooding young
chicks (7 days old) to protect them from detrimental
weather. Our results highlight measurable effects of
weather patterns on avian behaviour at a key stage of the life
cycle. Changes in weather conditions predicted for this region
will likely further benefit this range-expanding species.

The polychaetous annelid Diopatra biscayensis Fauchald et al., 2012 was recently described from the Atlantic coast of France. It has been the subject of a plethora of publications dealing with its importance in the field of ecology: from its role as an ecosystem engineer, being an indicative species of climate change in western Europe to questions of whether it was native or introduced to the old continent, spawning theories about its hypothetical routes of introduction and spreading. We have redescribed D. biscayensis, traced its biogeographical history in the Bay of Biscay through examination of old museum holdings and studied its ecology and reproductive biology throughout a one year period from a northern Spain estuary, showing for the first time that the species is a protandric simultaneous hermaphrodite. The annual spawning season is from early August to late September, when large numbers of oocytes of 260 mm diameter were deposited in gelatinous egg masses attached to the parental tubes. Early trochophores developed in the jelly mass by 4e6 h, 3-chaetiger metatrochophores after 48 h, and the jelly mass had totally disintegrated by 72 h, releasing the lecithotrophic larvae. Our studies have clarified the morphology and reproductive pattern of D. biscayensis, documented that the species has inhabited the European waters for more than a century and we hope that these findings will serve as a basis to robust ecological studies and hypotheses concerning this and the related species.

The reproductive cycle of the sub-Antarctic spatangoid sea urchin, Abatus cavernosus, was examined during a 2-year period in southern Patagonia, Argentina. The population studied is the northernmost known coastal population in the austral oceans, and is influenced by a greater annual range of seawater temperature than other Abatus species. The sex ratio of the overall A. cavernosus population did not differ significantly from 1:1, but was not homogeneous across size classes. A clearly defined annual reproductive cycle was found. Spawning occurred from May to July and was synchronous between sexes. Females were observed to be brooding within a 9-month period, from May to February. Juveniles were released during the austral summer, from January to February. The length at which 50% of the females were brooding occurred at a test length of 25.9 mm. A. cavernosus had a large egg size (mean diameter = 1.4 mm) and low fecundity (maximum = 57 eggs per female) compared to closely related species. The number of eggs within each brood pouch was highest in larger anterior brood pouch, which is close to two gonopores, as opposed to the other anterior and two smaller posterior pouches. Significant interannual variation was observed in gonad cycles, fecundity, and embryo development such as: brood size decreased during 2001; adjusted gonad dry weight and fecundity were higher during 2003. Hypotheses concerning the gonadal and brooding cycles and fecundity of sub-Antarctic and Antarctic Schizasteridae are discussed.

The reproductive cycle of the sub-Antarctic spatangoid sea urchin, Abatus cavernosus, was examined during a 2-year period in southern Patagonia, Argentina. The population studied is the northernmost known coastal population in the austral oceans, and is influenced by a greater annual range of seawater temperature than other Abatus species. The sex ratio of the overall A. cavernosus population did not differ significantly from 1:1, but was not homogeneous across size classes. A clearly defined annual reproductive cycle was found. Spawning occurred from May to July and was synchronous between sexes. Females were observed to be brooding within a 9-month period, from May to February. Juveniles were released during the austral summer, from January to February. The length at which 50% of the females were brooding occurred at a test length of 25.9 mm. A. cavernosus had a large egg size (mean diameter = 1.4 mm) and low fecundity (maximum = 57 eggs per female) compared to closely related species. The number of eggs within each brood pouch was highest in larger anterior brood pouch, which is close to two gonopores, as opposed to the other anterior and two smaller posterior pouches. Significant interannual variation was observed in gonad cycles, fecundity, and embryo development such as: brood size decreased during 2001; adjusted gonad dry weight and fecundity were higher during 2003. Hypotheses concerning the gonadal and brooding cycles and fecundity of sub-Antarctic and Antarctic Schizasteridae are discussed.

Anasterias minuta is an oral-brooding sea star and one of the main predators of intertidal benthos in Patagonia, Argentina. The aims of this study were to: (1) assess the temporal pattern of feeding and brooding, (2) evaluate the effect of body size, tidal height and temperature on feeding and brooding, (3) evaluate temporary changes in digestive and sexual organs and (4) investigate the relationships between the predatory and brooding activities. Females do not feed during the brooding period. Spawning proceeded during March. The brooding period was from March to November, with a maximum in May. The population feeding rate varied seasonally, with a maximum in December and a minimum in May. The feeding rate was positively related to water temperature and sea star size; but not with tidal height. An annual cycle exists for pyloric caeca weight in both sexes; lowest values were found during winter, due to brooding female starvation, and a possible decrease in feeding rate of non-brooding females and males. No inverse relationship was found between the pyloric caeca and gonad weights in females, but a lag of 1 month was observed in males, being the maximal pyloric caeca development before the maximum gonad weight, suggesting nutrient translocation.